Single Qubit Characterization Sequences

Simple spectroscopy and coherence experiments on a single qubit.

Initial setup

See Auspex example notebooks on how to configure a channel library.

For the examples in this notebook, we will the channel library generated by running ex1_QGL_basics.ipynb in this same directory.

q1 was already defined in the example channel library, and we load it here

Keep in mind that recreating q1 at this stage would give a warning, and try to update the existing qubit to reflect the newly requested parameters: i.e.

Sequences

Pulsed spectroscopy sequence

A single sequence with a long saturating pulse to find qubit transitions. The specOn option turns the saturation pulse on/off as this sequence is also useful with just a readout pulse for cavity spectroscopy.

Rabi Nutation sequences

For spectroscopy or calibration purposes we can perform a variable nutation angle experiment by varying either the amplitude or width of the excitation pulse.

Coherence Time Measurements

T$_1$

T$_1$ can be measured with an inversion recovery variable delay experiment. The sequence helper function tacks on calibration experiments that can be controlled with the calRepeats keyword argument.

T$_2$

T$_2^*$ is usually characterized with a 90-delay-90 experiment where as the Hahn echo removes low frequency noise and that causes incoherent loss and recovers something closer to the true T$_2$. The delay parameter is the pulse spacing and so the total effective delay in the Hahn echo will be 2 times this plus the 180 pulse length.